Melanin is a naturally occurring coloring matter, and is found as a chromoprotein in hair, dark skins, certain insects and plants. With age, the body produces less melanin, and as a result, hair turns grey or white.
In the past, melanin has been applied to hair as a dyeing agent. An example can be found in U.S. Pat. No. 5,273,550 to Prota et al., in which an aqueous composition containing 5,6-dihydroxyindole (DHI) is applied to the hair, and the DHI diffuses into the hair shaft and turns into melanin via a dopa-oxidant reaction.
Other hair dyeing techniques and solutions are typically based on the use of harsh chemicals. For example, U.S. Pat. No. 4,453,941 to Jacobs et al. describes a method of dyeing hair using N-acetyl-dopamin and omega-amino acid. The hair was wetted with N-acetyldopamine and beta-alanin solutions.
U.S. Pat. No. 4,775,527 to Bires et al. describes the use of an aqueous preparation on the basis of melanin dissolution and/or oxidation of a hair colorant dye intermediate, which contains as a swelling and penetration agent an N-alkyl pyrrolidone with different alkyl groups.
U.S. Pat. No. 4,834,767 to Helioff et al. describes another example of a hair dyeing process using a swelling and penetration agent. The agent of choice is a quaternized amino lactam.
U.S. Pat. No. 5,173,085 to Brown et al. shows the prolonged formation of melanin from 5,6-dihydroxindole used with the subsequent use of hydrogen peroxide solution and oxidizing in air.
U.S. Pat. No. 5,279,618 to Prota et al. teaches a combination of dopa, oxidant and couplers, which improve and speed up the process of hair dyeing.
Many of the foregoing references describe methods of hair dyeing that are based on the natural process of melanin developing from its precursors containing several dozens of chemical compounds. However, the concentration of dyeing agents, which would be enough for diffusion of dyeing agents is formed slowly. Thus, these methods are time consuming, and only the use of the ions of transitory metals and the strong oxidants might slightly accelerate it. Moreover, the use of mixtures, including the active oxidants, can be harmful to the hair.
There have been a variety of devices developed over the years for introducing treatment solutions to the hair and scalp. Representative examples include U.S. Pat. No. 4,090,522 to Donley et al. and U.S. Pat. No. 4,691,720 to Schmitz. In the former, a comb is provided with fluid-communicating teeth for applying a medication to the scalp. Fluid flow is by gravity. In the latter, a comb is used for applying dye to hair.
In some cases, electric devices have been used to apply an electric field to the scalp. U.S. Pat. No. 1,099,062 to Laposkey describes a device in which an electric current is induced in the scalp of the user. U.S. Pat. No. 1,724,984 to Wildey describes a comb having two rows of teeth that are electrically coupled to opposite terminals of a battery. A light bulb is connected between the rows of teeth.
In none of the above references has it been suggested how to affix an environmentally safe, naturally occurring dyeing agent to hair on a relatively long term basis.